Resorcinol (meta-dihydroxybenzene) is an industrial chemical of substantial significance. Its preparation is usually carried out through the high temperature (about 300.degree. C.) alkali fusion of meta-benzenedisulfonic acid. For chemical, as well as environmental reasons, this process is disadvantageous. The Hock process of preparation of phenol was extended for the preparation of resorcinol through meta-diisopropylbenzene dihydroperoxide. However, the existence of two hydroperoxide groups simultaneously present in the intermediate dihydroperoxide can result in the formation of an increased number of by-products, particularly as the rate of the reaction is substantially slower than that of cumene. U.S. application Ser. No. 130,401 filed Mar. 14, 1980 describes ways to overcome some of these difficulties with the use of superacidic catalysts. Nevertheless, there is a practical need for improved preparation of resorcinol from readily available alternate starting materials, particularly phenol itself.
The only related approach, so far reported, is to be found in U.S. Pat. No. 3,028,410 (1962) describing the preparation of dihydroxybenzenes through sulfuric acid catalyzed decomposition-rearrangement (i.e. Hock-reaction) of the corresponding hydroperoxides. Inter alia, this patent describes examples of the preparation of resorcinol from meta-isopropylphenol in the form of its phosphate, acetate or methyl ether derivatives, by preparing the related hydroperoxides and their subsequent acid catalyzed conversion. The preparation of pure meta-isopropylphenol substantially free of other isomers, however, so far, was not possible and mixtures of the isomers are extremely difficult and costly to separate. Further, the Hock reaction of substituted isopropylbenzene hydroperoxides, can result in significantly increased number of by-products and low yields. Thus, no practical preparation of resorcinol from phenol, through meta-isopropylphenol was, until now, known.